18221985 has 24 divisors (see below), whose sum is σ = 31711680. Its totient is φ = 9679392.

The previous prime is 18221953. The next prime is 18221989. The reversal of 18221985 is 58912281.

It is not a de Polignac number, because 18221985 - 2⁵ = 18221953 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18221989) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13156 + ... + 14474.

It is an arithmetic number, because the mean of its divisors is an integer number (1321320).

Almost surely, 2^18221985 is an apocalyptic number.

18221985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18221985 is a deficient number, since it is larger than the sum of its proper divisors (13489695).

18221985 is a wasteful number, since it uses less digits than its factorization.

18221985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1637 (or 1634 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 18221985 is about 4268.7217056163. The cubic root of 18221985 is about 263.1470838471.

The spelling of 18221985 in words is "eighteen million, two hundred twenty-one thousand, nine hundred eighty-five".